The present invention relates to a remote operation wire line core sampling device equipped with a core barrel for investigating bed rocks and deposits at a sea-bottom by using a stabilized sea-bottom core drill.
In conventional sea bed sampling, there are two methods. In other words, one is a method for collecting samples on a sea-bottom surface by using a dredge that linearly collects samples from the sea-bottom surface, or a grab that collects samples spread over a given width from a given place on the sea bottom surface. The other is a method for collecting samples at a given depth from the sea bottom surface. In a method generally adopted when taking samples at a depth from the sea-bottom surface, a tool called a corer is used, and a sampling tube called a core barrel is pierced through a bottom material of the sea bed to take the samples. While the corer, which utilizes its own gravity and initial piercing velocity, can pierce ground by ten and several meters at a maximum when the ground is soft, its capacity is substantially reduced in case of a sand bed or a somewhat hard stratum, and sample taking is impossible when the bottom material is rock.
FIG. 6 shows a conventional over-shot assembly for underground use (for horizontal boring). A lifting dog 9 is biased in a closing direction by a lifting dog spring 10. The over-shot assembly has a piston 33 in contact with an inner wall of a drill rod and is pushed in toward a hole bottom by a supply water pressure from above. At this time, a valve sleeve 31 is set by using man power in such a way as shown on the right-hand side of FIG. 6 against force of a valve spring 32, and an outlet of a water passage 34. That is, an opening adjacent to an upper side of the valve sleeve 31 is closed, whereby an increase in pressure is to be expected. At this time, a lower end of the valve sleeve 31 is at a shoulder portion 9-1 of a lifting dog handle 9-2. When the lifting dog 9 is engaged with a spear head 25 of an inner tube assembly, a forward end of the lifting dog 9 is opened, and the lifting dog handle 9-2 is diminished, so the valve sleeve 31 is caused to slide to a lowermost position by the force of the valve spring 32 as shown on the left-hand side of FIG. 6. At this time, the outlet of the water passage 34, that is, an opening adjacent to the left-hand side of the valve sleeve 31 is opened, so a reduction in supply water pressure is to be observed, and it is possible to ascertain that the lifting dog 9 has been fit-engaged with the spear head 25 of the inner tube assembly. At this time, the lifting dog handle 9-2 is situated at a lifting dog handle window formed in the valve sleeve 31. When the forward end of the lifting dog 9 is to be opened to detach the inner tube assembly, the opening operation is performed by holding the lifting dog handle 9-2 by hand.
FIG. 7 shows another conventional water swivel assembly for underground use. A spindle 35 is screw-connected to an uppermost portion of a drill rod and adapted to rotate, is isolated from a non-rotating portion by a ball bearing 36, and watertightness is maintained between a rotating portion and a non-rotating portion by a packing set 37. A water supply hose 43 is attached to a pipe bushing 38, and a wire rope passes through a small hole 41 at a top, and extends to an interior of a tube while maintaining watertightness by use of a wire rope packing 39. A wire rope is wound up by a winch (not shown) by way of a rope sheave 40.
As compared with an ordinary corer, which pierces through a bottom material solely by virtue of gravity and piercing velocity, a stabilized sea-bottom core drill, which has a rotary device and a feeding device and which can rotatingly pierce the bottom material while performing digging through rotation of a core bit at the forward end, is capable of sample collection regardless of hardness of the bottom material, and can exert a remarkable capacity in sea bottom sampling. On the other hand, in the stabilized sea-bottom core drill, continuous core sampling cannot be effected without letting in and out a core barrel a large number of times. Therefore, it was required to repeat retrieval and reinsertion of the core barrel and a drill rod each time. An example of retrieval is performing a next stroke, and reinsertion means performing of a reverse stroke. The deeper a digging place becomes, the more frequent time of retrieval and reinsertion become in geometrical progression. Thus, due to difficulty in operating a ship connected by a dither cable and limitations in operation time, there was a limit to depth allowing core sampling through operation of the stabilized sea-bottom core drill. Operational procedures are in the following order: drill rod pulling out; drill rod unscrewing; chuck-opening/drill-head-raising; rod movement/accommodation through manipulator; drill head lowering; chuck closing; and return.
Further, in the conventional core sampling, each time sampling collection is effected according to an effective length of a core barrel, a core barrel and the drill rod are inserted into and pulled out of the boring hole, so a hole wall of the boring hole may collapse, thereby making it impossible for a newly inserted core barrel to reach the hole bottom. Debris of the hole wall collapsed would flow down to the hole bottom to mix into the sample to be collected, resulting in deterioration in sample quality, which was rather difficult to cope with.
In the case of wire line core sampling performed on the ground, a core barrel outer tube with a core bit mounted to a forward end thereof and a drill rod are not retrieved but solely an inner tube assembly containing a sample is retrieved on the ground through introduction of an over-shot and operation of a wire rope, with a new inner tube assembly being dropped into the drill rod to be automatically attached to the core barrel at the forward end. If this system could be applied to a stabilized sea bottom core drill, operation of retrieving/reinserting the drill rod would have been omitted and the above-mentioned problem of hole wall collapse must have been solved. Thus, application of this system has not realized and has been ended in a hope.
However, wire line core sampling performed on the ground has needed operation to be conducted by man power, such as introduction of an inner tube assembly and separation of the over-shot and the inner tube assembly. Thus, adoption of the wire line system to a stabilized sea-bottom core drill used at the sea-bottom has not been made so far.
As another conventionally known technique, an ordinary wire line sampler recovery device is disclosed (Patent Document 1). Further, there are disclosed a sliding tube containing an expandable latch equipped with a latch spring, an engagement member (spear head) arranged at an upper end thereof, and an over-shot assembly grasping this engagement member, and the like. (Patent Document 2).
[Patent Document 1] JP 07-11860 A (FIG. 3)
[Patent Document 2] JP 2903350 B (FIG. 4)